1. Field of the Invention
The invention relates to the machining of objects.
2. Description of the Related Art
Automotive transmissions contain a bearing which is inserted in a so-called governor bore. As a transmission ages, leaks tend to develop around the bearing thereby affecting the performance of the transmission.
Since replacement of a transmission is costly, it has become the practice to rework a leaking transmission. Thus, the bearing is removed and the governor bore smoothed by means of a cutting tool. A new bearing is then inserted in the governor bore.
The cutting tool consists of a cutting head mounted on one end of a shaft. To align the cutting tool with the governor bore, a tool holder or guide is secured to the transmission. The guide has a passage which registers with the governor bore and receives the shaft of the cutting tool.
The transmission and the guide are provided with complementary centering portions which serve to center the guide with respect to the transmission. The transmission further has a pair of threaded holes, and the guide has a matching pair of holes which are brought into alignment with the holes in the transmission when the guide is to be secured to the transmission. The guide is connected to the transmission by screws or bolts which are inserted in the holes.
Automotive transmissions come in a wide variety of designs and the threaded holes in different transmissions have different relative positions. Moreover, the centering portions of different transmissions differ from one another. Consequently, a large stock of guides must be kept on hand. This is costly inasmuch as the guides are expensive. Also, the guides are relatively bulky and take up a large amount of space.
In addition to the drawbacks associated with the guides, the cutting tools available today are not entirely satisfactory for the reworking of governor bores.